Thermostat for scales



J. S. @GSBURY THERMOSTAT FOR SCALES Filed Feb. 5, 1932 ATTORN EY-Patented May 5, 1936 UNITED STATES PATENT OFFICE THERMO STAT FOR SCALESApplication February 3, 1932, Serial No. 590,605

10 Claims. (Cl. 26569) This case relates to spring scales andparticularly to a thermostat device therefor.

In spring scales, expansion and contraction of the spring resistant inaccordance with temperature aiTects the indication and accordingly, itis customary to provide thermostatic means for compensating the effectof temperature changes in the spring resistant.

The object of this invention is to provide several forms of a novelthermostatic device for compensating effect of temperature changes on aspring resistant.

Various other objects and advantages of my invention will be obviousfrom the following particular description of one form of mechanismembodying the invention or from an inspection of the accompanyingdrawing and the invention also constitutes certain new and novelfeatures of the construction and combination of parts hereinafter setforth and claimed.

In the drawing: Fig. 1 is a plan view of a lever provided with the novelthermostatic device,

Fig. 2 is a side View of the lever partly in section, and

Fig. 3 is a detail of a modification. Referring to the drawing andparticularly Figs. 1 and 2, in detail, It represents a base lever of 2.Dayton spring scale such as shown, for example, in Patent No. 1,355,499.The intermediate portion of the lever is bifurcated, the furcationsbeing joined by a cross brace or web I I. The inner end I2 of the leverextends centrally of the furcations, being on the longitudinal axis ofthe lever and has a guideway therethrough to guide a rod I3 formovement.

The rod is provided at the forward or nose end with nose iron I4 havinga V-shaped bearing groove resting on a knife edge I5 of a stirrup I6connected by tape II to the automatic counterbalancing and indicatingmeans (not shown). At the rear, the rod I3 passes through and is looselyuided in a hole I8 in the web I I. The rear end of the rod is formedwith a threaded portion I9 0 passing through a hole in a circular bandor ring 20 and is held in adjusted position by nuts 2|,

one on each side of the band. Diametrically opposite the connection ofthe rod I3 thereto, the band 20 is secured to a bracket 22 fastened byscrews 23 to the lever. Coil springs 25 are each fastened at one end tothe lever and at the other end to the band, their points of connectionwith the band being at diametrically opposite points and the springsextending oppositely in line with with the band. This diameter is atright angles to the line extending between the point of connection ofthe band to the plate 22 and its connection to the rod I3.

The band is of flexible metal such as steel or 5 composition materialsuch as bakelite and is formed as a true circle. When the two coilsprings 25 are hooked to the band, at 70 Fahrenheit, normal temperature,the band is distorted to an appreciable extent out of true circular l0shape, shortening it in the direction of the rod B. This is the normalposition of the band and the rod I3 is adjusted at this setting of theband to correctly set the nose iron I I, the setting of the nose ironobviously determining the effective 15 length of the lever which in turnaffects the operation of the counterbalancing and indicating means.

When the temperature increases, the springs 25 expand, thus permittingband 20 to spring 20 back towards true circular shape, the band thusexpanding in the direction of the rod I3 and moving the rod forwardly toincrease the effective moment arm of the spring resistants. Theexpansion of the band is proportional to the in- 25 .crease intemperature, the band never quite reaching its true circular form. Theincrease in the moment arm of the spring resistance acting on the levercompensates for the lower counterbalancing values of the springresistants with 30 increase in temperature.

When the temperature falls below 70, the springs 25 contract and shortenthe band in the direction of the rod I3, moving the latter rearwardlyand decreasing the effective moment arm 35 of the spring resistantswhich compensates for the increase in resistant strength of the springsas the temperature decreases.

In Fig. 3 is shown a modification in which a single coil spring 3!! isused to distort the band 20' in accordance with temperature foradjusting the position of the rod I3 carrying the nose iron. Spring 30extends diametrically of the band in the same direction as the rod I3and is hooked at the forward end to the free side of the band while atthe rear end, the spring is hooked to a fixed point of the band.

At normal temperature, the spring is of such length as to distort thering and shorten it in the direction of the rod. When the temperature increases, the spring expands and permits the band to move towards truecircular form thus moving rod I3 forwardly. When the temperaturedecreases, the spring contracts and shortens the band further in thedirection of the rod I3 moving the latter rearwardly.

While there has been shown and described and pointed out the fundamentalnovel features of the invention, it will be understood that variousomissions and substitutions and changes in the form and details of thedevice illustrated and in its operation may be made by those skilled inthe art without departing from the spirit of the invention. I thereforeintend to be limited only as indicated by the scope of the followingclaims:

I claim:

1. In a scale, a scale lever, a pivot, and a thermostatic device carriedby the lever and comprising an element movably mounted on the lever forcarrying the pivot, an endless flexible member connected to the element,and temperature responsive means for distorting said member to move theelement and pivot according to temperature variations.

2. In a scale, a load responsive lever, a pivot, an element movablycarried by the lever and coacting with the pivot, and a thermostaticdevice comprising a flexible member connected to the element, and aspring separately connected to the member to distort the latteraccording to temperature variations and thereby move the elementaccordingly to shift the pivot longitudinally of the length of saidlever.

3. In a scale, a load responsive lever, a nose iron, an element movablymounted on the lever and carrying the nose iron, and a thermostaticdevice comprising a flexible member connected to the element, and aplurality of springs connected to opposite sides of the member todistort it according to temperature changes and move the elementaccordingly.

4. In a scale including a load responsive element; at thermostaticdevice comprising a ring of flexible material connected to said element,and temperature responsive means for distorting said ring to move theelement.

5. In a scale as defined in claim 4, said means comprising a springeffectively connected to said ring.

6. In a scale as defined in claim 4, said means comprising a pluralityof springs connected to the ring at diametrically opposite points.

'7. In a scale as defined in claim 4, said means comprising a coilspring connected to the ring.

8. In a scale including a lever and a pivot carrying member movablelongitudinally of the lever; a thermostatic device comprising a ringconnected at diametrically opposite points to the lever and said member,and temperature responsive means for distorting the ring to move themember.

9. In a scale including a lever and a pivot carrying member movablelongitudinally thereof, a thermostatic device comprising a closed ringconnected at diametrically opposite points to the lever and the memberand a coil spring connected to the ring to distort it for moving themember.

10. The scale as defined in claim 9, there being two such coil springsconnected at diametrically opposite points to the ring.

JAMES S. QGSBURY.

